U02BB code meaning
Lost Communication With EVAP System Purge Pump
Network system Generic code U02xx codes Check engine light
What U02BB means
The purge pump actively pushes fuel vapour from the charcoal canister into the intake, which turbocharged engines need because they often lack intake vacuum. GM fits it to models such as Blazer, Encore GX, XT4 and Silverado 1500 as a separate unit with its own electronics, linked to the ECM by LIN. GM's 2025 engine tables describe U02BB directly: the ECM marks the pump as lost when its response frame has been absent for at least 250 ms, checked once the LIN channel has been active for 3 s at 11 to 18 V; GM rates it Type B, meaning the lamp waits for a second failing trip. Pump failures were common enough that GM extended coverage to 15 years/150,000 miles (N242484740), there with the P146x pump codes. While the pump is mute the canister is not purged and evaporative tests are suspended.
U02BB at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium, DIY possible
- Typical labor0.5 to 1.5 hours
- Clears after repairAfter a drive cycle
Symptoms of U02BB
- Check engine light after two drives
- Further EVAP or purge pump codes stored
- Possible fuel smell; driving itself usually normal
Common causes of U02BB
- Most likelyPurge pump electronics failed (known GM failure, extended coverage)
- PossibleLIN wire or pump connector damaged, corroded or unplugged
- PossibleNo supply from the actuator or powertrain relay, poor ground
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
EVAP purge pumpVehicle bus wiring
What each part of U02BB means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| BB | The exact fault in that area. |
What to do next
- Note U02BB and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about U02BB
What does U02BB mean?
U02BB means "Lost Communication With EVAP System Purge Pump". The purge pump actively pushes fuel vapour from the charcoal canister into the intake, which turbocharged engines need because they often lack intake vacuum. It is a generic code, so it means the same on every make.
Is it safe to drive with U02BB?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will U02BB fail an emissions test?
Yes, it can. U02BB is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is U02BB to fix?
Difficulty: medium. A typical repair takes 0.5 to 1.5 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will U02BB clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.